This invention is related in general to electronic communication, and more specifically, to timing measurement in a spread spectrum communications system.
Today's wireless communications systems are used to transfer digital information. In the case of radio-frequency (RF) spread spectrum satellite communications systems, it is critical to maintain accurate timing synchronization among multiple transmitters and receivers. For example, in a voice over Internet protocol (VoIP) system, it is necessary to maintain accurate clocking of data among separate users, or endpoints, since each endpoint is allocated a precise portion of the satellite transmission resources. Such resources can include time slots, bandwidth, power allocation, etc. Typically, the allocation of these resources may be determined by a clock or timing signal relative to a baseband frequency or carrier that is used to transmit signals to and from an orbiting satellite.
Due to the high speed of satellite data transfers, relatively long distances involved, delays or latency of data path processing, susceptibility of a radio signal to weather, directional transmission, and other factors, it is difficult to maintain synchronized timing signals among multiple endpoints.